Pre-eclamptic symptoms but low blood pressure & no protein in urine.?

I am 31 weeks pregnant and having pain under my rib cage and in my back on the same side. Spotty/blurry vision, constant headaches, and nausea. My BP and urine came back fine. I have had pre-e in a previous pregnancy witht he exact same symptoms except I had high BP and protein in urine too. What could be causing this since my BP is normal?